What a tragic story! ....The scary part is ..40 odd years ago..it could have been me!
I had found a 6" tapered nickle plated section of water supply line. Scrounging around in dads junk box, I found a round headed door hing pin, that was a tight press-fit into end of tube. This thing looked neat...with it's taper & rounded 'cascabal"..it was a dead ringer for an 1862 rifled gun.
I poured a charge of my home-grown black powder in, wadding, & dropped a 5/16" ball bearing in & rammed it home. I set up a target in front & ballanced the brl. on a short stump.
I actually got down behind it with a lit match over the primed touch-hole, taking careful aim at target....When a soft voice in my head said it might be a good idea to stand to one side..for the first shot anyways...That was the day my guardian angle must have started earning his overtime!
When the charge went off..there was a very load bang..brl. was blown about 5 feet away..target unscathed...But I started sweating when I held that warm barrel in my hands..that pressed-in "cascabal"...was nowhere to be found! But for the grace of GOD...there go I.